As shown in FIG. 5, a separate-type refrigeration device well known in the prior art includes a refrigerant cycle circuit A in which a compressor 1, a four-way switching valve 2, an outdoor heat exchanger 3, a heating pressure reduction mechanism 4B, cooling pressure reduction mechanisms 4A, and indoor heat exchangers 5 are connected together in series. The outdoor heat exchanger 3 is used as a condenser during cooling operations, and used as an evaporator during heating operations. The indoor heat exchangers 5 are used as evaporators during cooling operations, and used as condensers during heating operations. In addition, the refrigeration device is separated into an outdoor unit X which has the compressor 1, the four-way switching valve 2, the outdoor heat exchanger 3, and the heating pressure reduction mechanism 4B, and indoor units Y which have the cooling pressure reduction mechanisms 4A and the indoor heat exchangers 5. The outdoor unit X and the indoor units Y are connected together via refrigerant lines 6, 7.
In this refrigeration device, the cooling cycle and the heating cycle are switched by switching the four-way switching valve 2. In the cooling cycle, refrigerant circulates in this way: the compressor 1→the four-way switching valve 2→the outdoor heat exchanger 3→the heating pressure reduction mechanism 4B→the cooling pressure reduction mechanisms 4A→the indoor heat exchangers 5→the four-way switching valve 2→the compressor 1. In the heating cycle, refrigerant circulates in this way: the compressor 1→the four-way switching valve 2→the indoor heat exchangers 5→the cooling pressure reduction mechanisms 4A→the heating pressure reduction mechanism 4B→the outdoor heat exchanger 3→the four-way switching valve 2→the compressor 1. In the refrigeration device shown in FIG. 5, two indoor units Y are connected to one outdoor unit X. Reference numerals 8, 9 are shut-off valves.
The separate-type refrigeration device described above produces a differential in the quantity of refrigerant needed by means of the distance between the outdoor unit and the indoor units. Because of this, there will be a need to charge the refrigeration device with the optimal quantity of refrigerant onsite. For example, conventionally a refrigerant charging operation is performed in which the outdoor unit X is charged in advance with a predetermined quantity of refrigerant, and then during installation onsite, an additional quantity of refrigerant is added in accordance with the length of the refrigerant lines 6, 7 that connect the outdoor unit X and the indoor units Y.
The aforementioned refrigerant charging is normally carried out while creating a vacuum in the refrigerant cycle circuit A. However, in situations in which refrigerant is not placed into the refrigerant cycle circuit A, as shown in FIG. 5, with the refrigerant cycle circuit A in the cooling cycle state (cooling operational state), a method is employed in which a cylinder V in which refrigerant is collected is connected to the shut-off valve 8 on the liquid side refrigerant line 6 (the high pressure liquid line) side thereof, the shut-off valve 8 is closed, and the cylinder V is weighed on an electric scale E while charging refrigerant into the refrigerant cycle circuit A.
One problem that occurs when employing the aforementioned method is that a workman must be present for a long period of time in order to perform this task. For example, in a situation in which 10 refrigeration devices are to be installed, assuming 20 horsepower and 70 m of line in wintertime (20 kg of refrigerant charged), then it will take 2 to 3 hours to charge each refrigeration device, and thus the total time needed for the task will be 20 to 30 hours (3 to 4 days). Moreover, compared to charging the refrigerant in a factory, the task of charging the refrigerant onsite means that handling the lines will be difficult, work efficiency will be poor, and it will be difficult to correctly charge the refrigerant.
In addition, as noted above, when the amount of refrigerant to be charged is determined onsite during installation, the performance and reliability of the equipment becomes dependent on the quality of the onsite installation and thus, in some cases, the maximum performance of the refrigeration device cannot be realized.
Accordingly, it is known to employ a method (i.e., a chargeless method) in which refrigerant for local lines that have this degree of length is charged into the refrigeration device in advance, and when the local lines are short, the remaining refrigerant is stored in a receiver or the like inside the refrigerant cycle circuit. However, in this method, when the lines are short, unneeded refrigerant is always charged in the receiver or the like, and not only is the reliability of the equipment worse, but a receiver of an unnecessary size is needed and an unnecessary amount of refrigerant is needed. As a result, problems such as an increase in costs, an increased burden on the user, and harmful impact on the environment will be produced. In particular, this problem will be conspicuous in systems (refrigeration devices) in which there is a large quantity of refrigerant, like with multi systems for buildings.